The present invention generally relates to brackets for holding liquid level sensors. More particularly, the present invention is directed to an apparatus for maintaining a liquid level sensor relative to a liquid outlet tube extending from an outlet of a liquid pass-through device.
Certain liquid pass-through devices, such as in-line fluid heaters and pumps, will be damaged if powered on without fluids. For example, the heating element in an in-line heater designed for heating liquids will typically burn out if operated in a dry condition as the heating element will not be able to dissipate the heat generated without the presence of liquid, thereby damaging the heating element. In a pump, operating in a dry condition can damage the internal mechanical parts by excessive friction or heat.
Therefore, it is common practice to install a liquid level sensor on the output side of such devices and interlock the sensor to the device's power in a manner in which the device can only be powered on when liquid is present. The liquid sensor is placed on the output side of the device to provide a means to electronically indicate when the liquid has flowed through the device, and therefore is safe to operate and power on. One liquid level sensor type commonly used for this application is a capacitive liquid level sensor. These sensors are desirable as they function outside the fluid path and therefore do not come in direct wetted contact with the process fluid, which is particularly desirable when the purity of the process fluid is important.
As the sensor reacts to the presence of liquid present in the tubing, a bracket is required to hold the sensor in place for proper operation. An unreliable sensor reading can result from improperly installing the sensor too close to the tubing or by changing the distance between the sensor and the tubing after calibration. Unreliable sensor readings can also result if the tubing sags, resulting in a change of distance between the tubing and the sensor. Moving the sensor farther upstream from the device could also result in faulty readings since a user can mistakenly place the sensor in a portion of the liquid path (tubing) that contains liquid in all conditions even though the liquid pass-through device does not contain liquid. This can happen, for example, in a section of piping similar to a P-trap or the like.
Therefore, there is a continuing need for an apparatus that will hold a liquid level sensor in such a manner so as to keep the distance between the sensor and the tubing fixed. Such an apparatus should not allow the tubing to sag in the section that the sensor is located. Moreover, such an apparatus should not allow a user to move the sensor to a different location of the tubing. The present invention fulfills these needs, and provides other related advantages.